Low pressure atomizer nozzle for oil burners



3,073,047 LOW PRESSURE ATGMHZER NOZZLE FGR OL BURNERS Arne FrommEnernarir, Sonderhorg, Denmark, assignor to Danfoss VE?) ingenior MadsClausen, Eismark, Nordborg, Denmark, a Danish firm Filed dan. 2, 1957,ser. No. 632372 Ciainras priority, appiicaton Denmark Mar. 21, 1956 3Ciainrs. (Cl. 239-405) The invention relates to a low pressure atornizernoZZle for oil burners and with a central oil feed pipe and primary airfeed passages surrounding the said oil feed pipe and opening into anatomizer head from which tangentially disposed guiding passages emanateinto which feed openings from the Oil feed pipe open in order to producea whirling motion and simultaneous atomization of the oil in an airstream having preferably conical surface and issuing from an atomizeropening provided centrally in the front face of the nozzle.

Low pressure atomizer noZZles of the aforesaid kind are known, but theysuffer from the drawback that they are apt to give an irregularatomization when fed with reiativeiy small amounts of oil, since the oilfed is liable to be divided into dreps instead of issuing as acontinuous stream, and these discontinuous drops will involve apulsating atomization with consequent irregular combustion andprecipitation of non-atornized oil drops on the inner surfaces of theOil-firing installation.

It is the obiect of the invention to devise the construction of a lowpressure atomizer nozzie having none of the aforesaid drawbacks, and anessential feature of a low ressure atemizing nozzzle according to theinvention is that between the oil feed pipe and the air feed passagesthere is provided a preferably cylindrical body, coaxial with the axisof the nozzle, the said cylindrical body being made of a material thatis permeable to the primary air, such as porons metal.

As a result, the primary air from the air feed passages penetrates theporous body and mixes with the amount of oil supplied through the Oilfeed pipe so as to form a frOth-iike mixture. The said mixture is then,partly by eiector action of the air in the tangentiaih disposed guidingpassages, partly by the pressure exerted by the air in the air feedpassages, passed as a continuous flow to the atomizing opening of thenoZZle, where the mixture is effectively atomized without any tendencyto drop formation with its consequent inconveniences.

According to the invention the porous body is detachabie and mountedbetween the atomizing head of the noZZie and a sleeve which is providedwith the air feed passages and constitutes a part of the oil feed pipe.

As a result, the porous body may be exchanged and, if necessary, cleanedin case its pores should be more or iess ciogged by impurities containedin the oii.

According to the invention the porous body has conical sealing snrfacesfacing both the atomizing head and the sieeve.

As a result, the porous body is Centered soieiy by the cone-shapedsurfaces resting in contact with the said parts of the noZZle.

According to the invention such surface of the porous body as faces theair feed passages or a pressure Chamber formed hy a widening of these isslightly truncated, having its largest diameter close to the atomizinghead.

As a result, the cross-section of the space between the surface of theporous body and the air feed passages is narrowed in the directiontowards the atomizing head, which affords an adaption of the amount ofair which is decreasing along the surface of the porous body because ofthe partial air penetration through the said porous body.

&078347 Patented Feb. 19, 18 53 Furtherniore, the surface available forthe air penetration will be increased in such an embodiment.

According to the invention the central passage of the porous body hasits largest diameter close to the atomizing head.

As a result, suction will be'produced by the oil flow through thecentral passage owing to this increase in diameter.

According to the invention the central passage of the porous body opensinto a mixing Chamber which is formed in the atomizing head and is ofgreater diameter than the central passage.

As a result, a turbulent flow of the froth-like oil/air' mix is producedat the place where the central passage joins the mixing Chamber, and thesaid flow increases the frothing in effective manner and reduces thesize of the air bubbles incorporated in the emulsion.

According to the invention the mixing Chamber is along thecircurnference of its inner wall provided with feed openings directedobliquely outwards to the tangentially directed guiding passages.

As a result, the oil/air mix flowing from the central passage cannot bepressed directly out through the feed openings, but, on the contrary,its central parts are intercepted by the end wall of the mixing Chamberopposite the central passage, whereby the turbulence of the mixture isfurther increased. At the same time the distance for the mix in thetangentially disposed passage is' increased, which stabilises thedirection of the spray in the conical air stream outside the atomizeropening.

According to the invention the surface of the end wall in the mixingChamber is convex and preferably of conical shnpe, which also increasesthe turbulence of the flow in suitable manner.

The invention will now be further described with reference to thedrawing, in which FIGURE 1 is a diametral section of a low Pressureatomizing nozzle according to the invention,

FGURE 2 is a section at right angles to the axis of the nozzle on theline 11-11 of FIGURE 1, and

FIGURE 3 is a section of same, at right angles to the aXis of the noZZleon the line ilL-iil of FIGURE 1.

The low pressure atornizing nozzle 1 shown in the drawing has a centraloi-i feed pipe 2 and a number of surrounding feed passages 3 for primaryair which open into an atomizing head 4 from which emanate tangentiallydirected guiding passages 5 in which feed openings 6 from the oil-feedpipe 2 open. The fuel oil, which is fed to the oil-feed pipe 2 at arelatively low pressure, flows through the feed openings 6 into theguiding passages 5 where it meets in a conical mixing dome, the primaryair supplied through the passages 3, whereby the oil is subjected to awhirling motion simultaneous atomization, so that a conically shapedair-oil stream is produced, issuing from the atomizer opening '7provided centrally in the front of the nozzle. Between the oil feed pipeZ and the air feed passages 3 there is according to the inventionprovided a preferably cylindrical body 8 which is coaxial with the axisof the noZZle and is made of a material that is permeable to the primaryair, such as porous metal. The primary air is thus able to pass from theair feed passages 3 through the porous metal and into the oil feed pipe2, where the air will cause the formation of a frothlike rnixture of airand oil, the said mixture being subscquently, by reason of the ejectoraction of the air stream in the guiding passages 5 in combination withthe pressure exerted by the air from the air feed passages 3 and thepressure exerted by the oil from the Oil-feed pipe 2, passed as acontinuous stream to the atomizer opening 7 of the nozzle. In theatomizer opening of the noZZle the rniXture is effectively atomizedwithout any tcndency to drop formation With its consequentinconveniences.

The porous body 8 is exchangeable and mounted between the atomizer head4 and sleeve 9 in which the feeding passages 3 for the primary air areprovided and which constitutes a part of the oil feed pipe 2, the porousbody having conical sealing surfaces 10 and 11 facing the sleeve 9 andthe atomizer head 4, respectively. The porous body 8 is Centered in thecavity Of housing l by the :aling surfaces so that an air pressureChamber 12 is defined in the cavity between the outer surface of theporous body 8 and the air-feeding passages 3. The surface of the body Swhich faces the pressure Chamber is slightly truncated, having itslargest diameter close to the atomizer head 4. Similarly the centralpassage 13 of the porous body 8 has its largest diameter close to theatomizer head 4, and where the latter joins the central passage 13 theatomizer head is formed with a mixing Chamber 14 which has a largerdiameter than the central passage 13. Along the circumference of itsinner wall the mixing Chamber 14 is provided with feed Openings 6,directed obliquely outwards and ending in the guiding passages 5. Theend wall surface 15 in the mixing chamber is preferably conical.

What I claim and desire to secure by Letters Patent is: 1. A lowpressure atomizer nozzle for oil burners comprising a hollow housingdefining an interior cavity and having a forward wall provided with acentral discharge opening, a central oil feed-pipe element disposed atleast partially in said cavity and provided with means defining primaryair feed passages surrounding said element and communicating with theportion of said cavity between said element and said forward wall forthe passage of air under pressure into said cavity portion, an atomizerhead in said cavity adjacent said forward wall and disposed to receiveOil feed interiorly from the interior of said element, said atomizerhead being formed with feed openings for passage of Oil therethrough andtangentiallydisposed guiding passages communicating with said feedopenings, land a porous channel-ferming member disposed between saidfeed-pipe element and said atomizer head, said body being coaxial withthe axis of the nozzle and being formed from a material which ispermeable to the primary air in said pressure Chamber to define acontinuous oil conducting passageway between said feed-pipe element andsaid atomizer head, said atomizer head and said porous member beingdimensioned to leave at least One peripheral pressure Chamber in saidcavity porton for axial flow of said air under pressure over theexteriors of said head and said porous body and space being providedbetween said atomizer head and the interior of said forward wall forpassage of said air from said Chamber across said passages and out saiddischarge opening.

2. A nozzle as defined in claim 1, wherein the porous member has conicalsealing surfaces facing the atomizer head and the feed-pipe element,respectively.

3. A nozzle as defined in claim 1, wherein the surface of the porousmember which faces the pressure Chamber is slightly truncated, havingits largest diameter close to the atomizer head.

4. A nozzle as defined in claim 1, wherein said porous member defines atapered centrally-disposed channel having its largest diameter close tothe atomizer head.

5. A nozzle as defined in claim 4, wherein the central passage of theporous body opens into the atomizer head defines a mixing Chambercommunicating with the channel of the porous member and having a largerdiameter than said channel.

6. A nozzle'as defined in claim 1, wherein said feed openings aredirected obliquely outwardly in a radial direction in relation to theaxis of said housing.

7. A nozzle as defined in claim 5, wherein the end surface of saidmixing Chamber defined by said atomizer head is convex.

8. A nozzle as defined in claim 5, wherein the end surface of said mixngChamber defined by said atomizer head is Conical.

References Cited in the file of this patent UNITED STATES PATENTS674,351 Atkins May 14, 1901 2,044,720 Fletcher June 16, 1936 2,772,120Olson Nov. 27, 1956 2,815,069 Garraway Dec. 3, 1957 2,825,602 RabbittMar. 4, 1958 2,854,285 Barton Sept. 30, 1958 FOREIGN PATENTS 585,595Germany Oct. 7, 1933 UNITED STATES PATENT OFFICE 'CERTIFICATE OFCORRECTION Patent Non &078 047 February 19, 1963 Arne Fromm EnemarkInthe grant, (Only) line l, for "Arne Fromm, of Enemark, Sqndrborg,Dnmark," read Arne Fromm Enemark of sonderb orgv Denmark,

Signed and sealed' this 3rd day of 'september l93 (SEAL) Attest:

ERNEST w. SWIDERY 'I DAVID L. LADD Attestng Officer Commissioner OfPatents

1. A LOW PRESSURE ATOMIZER NOZZLE FOR OIL BURNERS COMPRISING A HOLLOWHOUSING DEFINING AN INTERIOR CAVITY AND HAVING A FORWARD WALL PROVIDEDWITH A CENTRAL DISCHARGE OPENING, A CENTRAL OIL FEED-PIPE ELEMENTDISPOSED AT LEAST PARTIALLY IN SAID CAVITY AND PROVIDED WITH MEANSDEFINING PRIMARY AIR FEED PASSAGE SURROUNDING SAID ELEMENT ANDCOMMUNICATING WITH THE PORTION OF SAID CAVITY BETWEEN SAID ELEMENT ANDSAID FORWARD WALL FOR THE PASSAGE OF AIR UNDER PRESSURE INTO SAID CAVITYPORTION, AN ATOMIZER HEAD IN SAID CAVITY ADJACENT SAID FORWARD WALL ANDDISPOSED TO RECEIVE OIL FEED INTERIORLY FROM THE INTERIOR OF SAIDELEMENT, SAID ATOMIZER HEAD BEING FORMED WITH FEED OPENINGS FOR PASSAGEOF OIL THERETHROUGH AND TANGENTIALLYDISPOSED GUIDING PASSAGESCOMMUNICATING WITH SAID FEED OPENINGS, AND A POROUS CHANNEL-FORMINGMEMBER DISPOSED BETWEEN SAID FEED-PIPE ELEMENT AND SAID ATOMIZER HEAD,SAID BODY BEING COAXIAL WITH THE AXIS OF THE NOZZLE AND BEING FORMEDFROM A MATERIAL WHICH IS PERMEABLE TO THE PRIMARY AIR IN SAID PRESSURECHAMBER TO DEFINE A CON-